Enhance the Gmail and Inbox experience

Use the Gmail REST API to add Gmail features to your app, granting it
access to threads, messages, labels, drafts, and history. The API is
easy to use with modern web languages and
Google API client libraries.

Create a Gmail Add-on to let your users interact with your apps and services directly—without ever leaving Gmail. You use Apps Script to create an add-on that can extend Gmail behavior, add functionality, and connect to other G Suite products like Google Calendar.